1. Field of the Invention
The present invention relates to a technique of locking a vehicle placed on a chassis dynamometer.
2. Description of the Related Art
In recent years, chassis dynamometer has been used for performance test of vehicles including automobiles. In this sort of performance test of vehicles, a test vehicle is set on the chassis dynamometer, and is then artificially driven according to a predetermined driving pattern, while simulating an actual road test, so as to enable measurement of various performances and characteristics, including fuel consumption, horse-power performance, and so forth.
On the chassis dynamometer, the test vehicle is necessarily positioned while placing the driving wheels thereof at desired positions on the rollers, and locked so as to avoid dislocation of the test vehicle after start of the test run. Conventionally, this sort of locking of the test vehicle has been accomplished by using belts or the like, so as to couple the test vehicle and locking portions disposed on the pit in the front and rear of the test vehicle, and to pull the individual belts (see Japanese Patent Application Laid-Open No. 10-307082, for example).
For the case of locking the test vehicle using the belts or the like, it is ideal to haul the test vehicle while keeping the driving wheels thereof stayed on the desired positions on the rollers, and to optimize traction force (tension) generated on the belts as a result of hauling so that the test vehicle may be locked in a stable manner.
However, no matter how the test vehicle could be hauled by the belts, while keeping the driving wheels of the test vehicle stayed on the desired positions on the rollers, it has not always been easy to optimize tension of the belts as a result of hauling. This is because, as for the belts stretched under tension while keeping a certain angle of inclination away from the test vehicle as disclosed in Japanese Patent Application Laid-Open No. 10-307082, it may be difficult to estimate correct force for optimizing the tension of the belts as a result of hauling, unless otherwise relative angle formed between the belts and the test vehicle may properly be detected. If the tension of the belts were uneven, the test vehicle may begin to roll when the test run starts, upon release of braking force which has been exerted to the test vehicle in the rest state, so that the vehicle performance test may adversely be affected.